Dr. Jeff Masters' WunderBlog

California fires could reach record levels in 2008

Posted by: Dr. Jeff Masters, 9:42 PM GMT on June 25, 2008

An unusually early and dangerous fire season has hit California, where at least 33 fires burning over a total of 190,000 acres are active, according to the Interagency Fire Center. The fires were sparked over the weekend when an unusually far southward-moving storm system brought numerous thunderstorms to central and northern California. Over 8,000 lightning strikes hit the region. Most of these strikes were not accompanied by rain, since a very dry atmosphere at low levels caused much of the thunderstorm rain to evaporate before reaching the surface. The lightning strikes ignited an unusual number of fires, due to exceptionally dry vegetation in California. This year, the state experienced its driest spring season (March-April-May) since record keeping began in 1895, and much of the state is in moderate to severe drought.

Figure 1. Visible satellite image from NASA's Aqua spacecraft on Monday, June 23, 2008, showing smoke from hundreds of wildfires sparked by lightning in California. The red regions show where the satellite's sensor detected fires burning. The smoke has created air pollution levels in excess of the federal standards for fine particulate matter (PM2.5) over much of California's Central Valley. Image credit: NASA.

The forecast
With the dry season only beginning, it could be a record fire year in California. Even before last weekend's lightning storms, California had already seen an unusually large number of destructive wildfires, according to CalFire--90,000 acres had burned, compared to 42,000 acres during the same period last year. It is not unusual for large portions of the state to receive no rain at all in July and August, such as occurred last year (Figure 2). The jet stream typically moves far enough north in summer that the migrating low pressure systems that bring California most of its rain only hit the northernmost portions of the state. With high fuel levels due to a century of misguided fire suppression efforts, moderate to severe drought gripping the state, no rain in sight for months to come, and an above-normal chance of warmer than average temperatures forecast this summer for the state by NOAA's Climate Prediction Center, expect a record fire season in California.

Figure 2. Observed precipitation over California during 2007. Much of the state received no rain at all during July and August, which is a common occurrence. A little bit of thunderstorm activity did make it into the easternmost portion of the state, thanks to moisture flowing north-westward from the Arizona Monsoon. However, the Sierra Mountains block this moisture from reaching the central and western portions of the state. Image credit: NOAA.

Tropics
It's quiet in the tropical Atlantic. There are no threat areas to discuss, and none of the models are forecasting tropical storm formation in the next seven days. Beyond a week from now, the GFS is hinting that the region off the coast of Africa could see some development, but it is still probably too early for this too occur, despite warmer than average sea surface temperatures in the region.

Jeff Masters

San Bruno Mountain Fire - Cresting the Ridge (ajkimoto)

Photo taken as the fire crested the ridge of San Bruno Mountain

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1202. Drakoen 4:51 PM GMT on June 27, 2008
1185. IKE 4:40 PM GMT on June 27, 2008 12Z GFS is further west and south with the African wave(system?), on this run compared to the 6Z run. Yep which makes the forecast somewhat more believable since the storm won't be heading into those sub 26C waters. Waters above 26C are needed to maintain organized convection. Member Since: October 28, 2006 Posts: 57 Comments: 29010

1203. IKE 4:52 PM GMT on June 27, 2008
1194. Beachfoxx 11:45 AM CDT on June 27, 2008 It is hurricane soup out there. Yep, Surfmom it is... My plans for checking water temps may have just changed. Have some serious thunder booming... Hey Ike! A couple of nasty storms this week... Did you know those young boys who lost their lives last Sunday during that T-Storm? So tragic. Their grandfather has insurance with me. Tragic....yeah...it's clouding up here too... Member Since: June 9, 2005 Posts: 23 Comments: 37044

1205. prophetofdoom 4:52 PM GMT on June 27, 2008
cool, its scary to live here we arent safe anymore.

1206. IKE 4:55 PM GMT on June 27, 2008
1200. 7544 11:49 AM CDT on June 27, 2008 1091. StormW 2:51 PM GMT on June 27, 2008 1083. IKE 10:47 AM EDT on June 27, 2008 Appears to be moving west...definitely a circulation with it. Slow WNW motion. would you say the spin is around 7n/ 34 w with this wave Close to there. Member Since: June 9, 2005 Posts: 23 Comments: 37044

1207. GOLSUTIGERS 4:55 PM GMT on June 27, 2008
Thanks StormW. We have had some good afternoon storms in Baton Rouge the last few days with lots of lighting and hail. Suppose to continue though Monday. Member Since: June 25, 2008 Posts: 0 Comments: 37

1208. Drakoen 4:56 PM GMT on June 27, 2008
Member Since: October 28, 2006 Posts: 57 Comments: 29010

1209. Beachfoxx 4:56 PM GMT on June 27, 2008
Ike, Broke my heart for the family.... New blog up. Member Since: July 10, 2005 Posts: 153 Comments: 29285

1210. prophetofdoom 4:56 PM GMT on June 27, 2008
we had hail and lost power in metairie yesterday.

1211. pottery 5:00 PM GMT on June 27, 2008
Hello all. Nice weather here at 11n 61w today.( Trinidad) Showers, sunshine, clear sky, green vegetation, cool breeze. Temp 90f Humid. 66% Press, 1013 falling. And I dont work on Friday anymore....... Member Since: October 24, 2005 Posts: 0 Comments: 20708

1212. 69Viking 5:03 PM GMT on June 27, 2008
1194. Beachfoxx I read about it, so sad. I have a 10 year old already shopping for his first boat. By the time he gets one I'll make sure he has a good understanding of the weather and how quickly it can change for the worse. Until then he can just remain the co-captain on my boat where I'll keep us both out of storms like the one that did those boys in. Member Since: August 25, 2006 Posts: 0 Comments: 2247

1213. zoomiami 5:29 PM GMT on June 27, 2008
Belated thanks for the answers - had to go back to work! Member Since: August 13, 2007 Posts: 10 Comments: 4064

1214. 786 5:42 PM GMT on June 27, 2008
Okay here is what my understanding is thus far, I hope it helps those who are kinda confused like me: Vorticity: the rotation of air in a horizontal plain. Positive vorticity means that the rotation is cyclonic (anti-clockwise). 850hPA represents the atmospheric pressure at the altitude of 1500m - the distance is measured from sea-level. The more positive the vorticity is, the stonger the cyclonic flow and at the 850hPa level higher positive vorticity = higher chance of unsettled weather. MJO = Madden Julian Oscillation which is a 30-60 day cycle of flucuations in tropical rainfall. The wave starts in the Indian Ocean and travels East at 800km/day!! It is always in one of 8 phases. We are currently in phase 7 which shows that the Atlantic is within the "blue zone" of the MJO's = enhanced rainfall. When the "MJO is ascending" air is rising and therefore dry air is reduced, moisture can build up which is favourable for convection. ENSO is the state of the Southern Oscillation. It ranges from El Nino, Neutral, La Nina. La Nina to Neutral produce the most favourable conditions for tropical development as wind shear is lower, temperatures in the Atlantic are higher etc. NAO is the Northern Atlantic oscillation which is the difference of sea-level pressure between the Icelandic low and the Azores high (constants in the earth's atmosphere). It controls the direction and strength of Westerly winds and storm tracks. A positive phase NAO means that there are there is below normal height and pressure across high latitudes in the Northern Atlantic and above normal height and pressure in the Central Atlantic, Eastern U.S and Western Eurpope. In a positive phase temperatures in the Easter U.S. are above normal. Along with the following: - subtropical ridge is stronger - the Bermuda high is higher and more Westward - there is reduced wind shear - the Easterly jet is increased During El Nino a negative phase NAO is more conducive for tropical development whereas during La Nina a positive phase is more conducive. In conclusion from my limited understanding, my first ever attempted forecast: seeing as we are in La Nina, MJO is producing enhanced rainfall in the Atlantic, we are in a positive phase of the NAO - over all climatology favours development at present. For the wave at 36w there is limited positive vorticity, the wave at 21w is displaying better cyclonic turning (positive vorticity). Shear in front of both waves is favourable (5-10 knots) and the shear tendancy map (which shows how the shear pattern has been in the last 24 hours), shows that shear in front of both the 21w and 36w wave is decreasing or otherwise at 5-10 knots. SSTs are higher than 27 degrees celsius (anything above 26. celsius can develop a cyclone)b and thats it Member Since: August 18, 2007 Posts: 0 Comments: 910

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